1. Field of the Invention
The present invention relates to a technique of compositing a physical space image and a virtual space image.
2. Description of the Related Art
In recent years, studies about an MR (Mixed Reality) technique have been extensively made (see patent reference 1). In the MR technique, a physical space image is sensed by a camera worn by an observer on the head. A virtual space image (CG (Computer Graphics) image) is generated based on viewpoint information representing the position and orientation of the viewpoint of the observer at the time of sensing. The virtual space image is composited on the physical space image to generate a composite image. The composite image is then displayed on a display device worn by the observer on the head.
Processing executed in the composition process has been proposed. That is, a period of time required for creating a CG image is predicted. The amount of movement of the observer's head (viewpoint) until the predicted period of time elapses is predicted. The CG image is generated based on the viewpoint which has been moved by the predicted amount, and is composited with the physical space image (see patent reference 2).
[Patent Reference 1] Japanese Patent Laid-Open No. 07-311857
[Patent Reference 2] Japanese Patent Laid-Open No. 2004-109994
However, the following problems arise in a method of compositing a physical space image and a CG image generated based on viewpoint information at the time of sensing the physical space image, and displaying the composited image.
To generate and display a composite image of a physical space image and a CG image, a series of processes including a process of sensing the physical space image, that of generating the CG image, and that of compositing the physical space image and the CG image are required. This causes a delay in displaying the composite image after the physical space image is sensed, as a matter of course. In particular, when the viewpoint moves quickly, the delay is conspicuous.
In a method of creating a CG image in advance based on a predicted amount of movement of the observer's viewpoint and compositing the CG image on a physical space image, a delay due to the CG image creation process shortens. However, there is an error between the viewpoint in the CG image and that in the physical space image. As a result, the observer who observes the composite image obtained by compositing the physical space image and the CG image experiences an unnatural impression with respect to the CG image.